This paper proposes LEAVES, a novel module that automatically learns data augmentation methods within a contrastive learning framework applied to biobehavioral time-series data. Conventional contrastive learning relies on data augmentation techniques, but finding optimal augmentation methods and parameters is difficult and time-consuming. LEAVES learns augmentation hyperparameters within a contrastive learning framework using adversarial learning. Experimental results on various biobehavioral datasets using SimCLR and BYOL demonstrate competitive performance compared to existing methods, significantly improving efficiency with a significantly smaller number of parameters (approximately 20) than existing methods (e.g., ViewMaker). LEAVES requires virtually no manual hyperparameter tuning, making it suitable for large-scale or real-time medical applications.